1. Field of the Invention
The present invention relates to an optical disc recording/reproducing apparatus for recording and/or reproducing information onto and/or from an optical disc such as a CD (Compact Disc) or a DVD (Digital Versatile Disc).
2. Description of the Background Art
Conventionally, there is an optical disc recording/reproducing apparatus for recording and/or reproducing information onto and/or from an optical disc, such as a CD or a DVD, which has concentric or centrifugal information recording tracks formed thereon, with the use of an optical head called an optical pickup. The optical pickup is configured to focuses and apply light of a semiconductor laser or the like onto an optical disc through an objective lens, receive the reflected light from the optical disc and output electrical signals corresponding thereto. The optical pickup moves in the radial direction of the optical disc.
An optical disc recording/reproducing apparatus allows an optical pickup to move to a predetermined position on an optical disc and focuses and applies light from the optical pickup to the recording tracks on the optical disc while rotating the optical disc, thereby recording and/or reproducing information onto and/or from the optical disc.
For reproducing information from the optical disc, the optical disc recording/reproducing apparatus performs “focus-on” (focus drawing) of light emitted from the optical pickup such that the focus point of the light is positioned on the optical disc surface and then performs “track-on” (track drawing) of the focused-on light such that the light is positioned on the recording tracks. These focus-on and track-on are performed by moving the objective lens in the direction perpendicular to the optical disc surface and in the direction perpendicular to the recording tracks, in accordance with electrical signals output from the optical pickup. Further, in the focus-on and track-on state, pits formed on the optical disc are detected on the basis of electrical signals output from the optical pickup; thus, information is read from the optical disc and the information is reproduced. Recording of information onto the optical disc is performed by forming pits on recording tracks of the optical disc with light which is emitted from the optical pickup and focused onto the optical disc.
Generally, on a reproduction-only optical disc on which music and images have been previously recorded, information indicating the content of recorded data in the optical disc and information about operation programs and the like are recorded at the innermost circumferential side of the recording tracks. Also, in the case of an optical disc onto which a user can record information, the information is successively recorded thereon from the innermost circumferential side of the recording tracks.
Consequently, for example, when an optical disc is mounted into the apparatus main body, the optical disc recording/reproducing apparatus performs an initial operation of reading information recorded at the innermost circumferential side of the optical disc and determines the type of the optical disc and the content of recorded data therein on the basis of the information read by the initial operation. Then, the optical disc recording/reproducing apparatus controls subsequent recording or reproducing operations. During the initial operation, the light from the optical pickup is focused-on and tracked-on at a prescribed initial position which is slightly closer to the outer periphery than the innermost circumferential side of the recording tracks with a slight margin.
On the other hand, if a user erroneously mounts an unrecorded optical disc into an optical disc recording/reproducing apparatus, the optical disc recording/reproducing apparatus will search for tracks including data recorded thereon. Therefore, in such a case, the optical disc recording/reproducing apparatus has been out of control while keeping searching for tracks, in some cases. More specifically, since no pit is formed at the position on which light from the optical pickup is focused on during the initial operation, the optical disc recording/reproducing apparatus can not perform track-on even if it tries track-on. As a result, the focusing fails and recorded information can not be read. Further, if focusing fails, the optical disc recording/reproducing apparatus retries track-on several times and determines that the optical disc is an unrecorded disc in the event of time-out, in many cases. Such determination requires a long time. Japanese Laid-Open Patent Publication No. 06-267179 discloses a method which determines whether or not sub-code signal components or synchronization signal components are read from an optical disc, as a method for determining an unrecorded portion other than the method employing time-out. Japanese Laid-Open Patent Publication No. 2003-263755 also discloses a method which determines recorded portions and unrecorded portions by confirming the detection period of pits.
However, any of the methods disclosed in the aforementioned publications require some time since they performs the determination after an optical disc is mounted and starts to rotate, then it reaches to a normal rotation speed and the preparation for the initial operation is completed.